In our concurrently filed copending application Ser. No. 219,677, which is entitled "Planar Multijunction Solar Cells", and the subject matter of which is hereby incorporated by reference, there is disclosed a new type of solar cell exhibiting a high output voltage. In brief, the solar cell in question comprises a multiplicity of voltage generating regions within a single semiconductor wafer, each of the regions forming a unit cell within the wafer and the unit cells being connected together in series so that the contributions of all of the cells are added together. Although the solar cell disclosed in the abovementioned application is obviously not limited to such a method, a specific exemplary method for making the planar multijunction cell disclosed in that application provides for the creation of the voltage generating regions in a flat surface of the planar wafer by implantation or diffusion of active and passive materials to form p+, metal, and n+ regions within the flat surface. The implanting of metal creates certain problems and the method of the present invention eliminates such implanting of metal and thus offers substantial advantages as compared with the technique discussed above.
Reference is made to the patents and other materials cited in the abovementioned application for a discussion of other prior art techniques of possible interest.